Stations uploaded with changed BFO-frequency

2 posts / 0 new
Last post
DL2WB's picture
Last seen: 3 years 8 months ago
Joined: 2010/09/03 - 12:20
Stations uploaded with changed BFO-frequency
Image icon WSPR_BFO_800Hz.jpg312.05 KB

Some operators (including me) want to receive and automatically upload spots with an Rx BFO frequency different to the 1500 Hz. The most common reason is that they want to use an Rx with a narrow Xtal Cw filter.
This helps in crowded bands - such as 30 m - and blocks out-of-WSPR-band signals.
While most modern DSP-based Trx can provide a filter center-frequency of 1500 Hz, the classic Xtal-based filters are fixed to e.g. 800 Hz center frequency.

So far my WSPR-X v0.8 installation - same on a recent WSPR installation - do not upload spots as soon as the Rx BFO setting is changed.

There are several forum topics that were created on that issue.

I found a quite simple solution for that problem:

Why not mix the 800 Hz signal out of the Rx up to 1500 Hz - digitally ?

I use the marvelous - and free - Spectrum Lab software by DL4YHF.

It took me less than 30 minutes from downloading to have it running.
See the attached screen shot.

Some remarks:
If you use your Rx in Cw mode, the Cw dial frequency is the TX frequency.
E.g. set the Rx to 10.1402 MHz CW for reception of the 30 m band WSPR section.

The above soltion runs reliably even on low-end hardware, such as my vintage 1.7 GHz WinXP laptop.

Regarding non-Windows systems, maybe Gnuradio could be used for mixing up the audio frequency?
I guess there is still some room for experiments.